1. Field of the Invention
The present invention relates to a method and system for terminating a PPP session in a dormant state of a mobile communication terminal and, more particularly, to a method and system for terminating a point-to-point (PPP) session in a dormant state of a mobile communication terminal, which is capable of preventing squandering of communication resources caused by reorigination of a physical layer upon termination of the PPP session between the mobile communication terminal and a mobile communication system during the dormant state of the mobile communication terminal.
2. Description of Related Art
When there is no data transmitted or received in a physical layer and a radio link protocol (RLP) layer for a predetermined time interval while a mobile communication terminal uses a data call (a packet data service or a socket data service), i.e. while a mobile communication terminal transmits/receives data to/from a mobile communication system after assignment of a traffic channel, the data call is released, i.e., the physical layer and RLP layer are down.
In the present invention, the socket data implies data transferred between a mobile communication terminal and a mobile communication system while the mobile communication terminal is not connected to a personal computer (PC). The packet data implies data transferred between a PC and a mobile communication system when a mobile communication terminal connected to the PC operates as a modem.
In a case of the socket data, the PPP layer and higher layers in a protocol stack of the mobile communication terminal are working while the physical layer is down. Meanwhile, in a case of the packet data, the PPP layer and higher layers in a protocol stack of the PC connected to the mobile communication and a resource management (RM) interface for interfacing the mobile communication terminal with the PC are working while the physical layer is down.
That is, the dormant state implies that the physical layer is down while a PPP session of the packet data or socket data is maintained.
Once the mobile communication terminal enters into a dormant state, the mobile communication terminal will remain in the dormant state till before reorigination of the physical layer caused by occurrence of data transfer.
However, the dormant state of the mobile communication terminal is not maintained unlimitedly when there is no data transfer in progress. In more detail, when there is no data transfer for a predetermined time interval after entrance into the dormant state, i.e., when there is no data transfer for a predetermined time interval from the start time to the expiration time of a session closure timer initiated at the entrance into the dormant state, or when a termination event occurs prior to the expiration of the session closure timer during the dormant state, the dormant state is released and the data transfer process is completely terminated.
In this case, conventionally, reorigination of a physical layer and reassignment of a traffic channel are performed for termination of the PPP session between the mobile communication system and the mobile communication terminal in the dormant state.
That is, when the session closure timer is expired or the termination event occurs prior to the expiration of the session closure timer during the dormant state of the mobile communication terminal, reorigination of the physical layer and reassignment of the traffic channel are performed and a PPP termination request message is transmitted. According to the PPP termination request message, the PPP session between the mobile communication terminal and the mobile communication system is terminated, resulting in termination of data transfer.
Accordingly, there has been a problem in that upon termination of the PPP session between the mobile communication terminal and the mobile communication system during the dormant state of the mobile communication terminal, reorigination of the physical layer and reassignment of the traffic channel are performed, resulting in squandering of communication resources.